1. Field of the Invention
The present invention relates to a method of manufacturing a flexible substrate having a thin film, a method of manufacturing an organic electroluminescent display device using the method, and an organic electroluminescent display device.
2. Description of the Related Art
Flexibilization of flat display devices such as organic electroluminescent display devices and thin-film transistor-liquid crystal display (TFT-LCD) devices has been studied in various ways. In order to make display devices have flexibility, a flexible substrate is used. Such a flexible substrate is usually made of a synthetic resin. However, since flat display devices require complicated processing conditions for forming an organic layer, a TFT layer for driving a display device, an electrode layer, and an oriented layer according to their characteristics, when a substrate made of a synthetic resin is used, the substrate or thin films formed on the substrate may be deformed under the processing conditions.
To overcome this problem, Japanese Patent Publication No. 2000-123971 discloses a method of manufacturing an organic electroluminescent display device using a substrate made of a moisture-proof film. The organic electroluminescent display device includes two facing insulation substrates, at least one of which has flexibility and at least one of which has light transmissivity. An electrode layer is formed on the inside of each substrate, and an organic layer having a luminescent layer is disposed between the electrode layers. The method of manufacturing this organic electroluminescent display device includes forming an electrode layer and an organic layer on one substrate, forming an electrode layer and an organic layer same as that on the one substrate on the other substrate, and combining the two substrates such that the two organic layers are in close contact with each other.
In the meantime, Japanese Patent Publication No. hei 9-7763 discloses another method of manufacturing an organic electroluminescent display device. In this method, a transmissive anode layer and an organic thin film are formed on one moisture-proof film, a cathode layer and an organic thin film are formed on another moisture-proof film, and the two moisture-proof films are combined. In order to increase adhesion between the organic thin films, when the two moisture-proof films are combined, a resin layer formed by scattering an organic material on a resin binder is used, and the two moisture-proof films are pressed at a temperature where the resin binder is softened.
In the above-described methods, the organic layers are separately formed, and therefore, it is difficult to align the organic layers when the two substrates are combined. Furthermore, adhesion between all of the organic layers formed in predetermined patterns cannot be increased.
U.S. Pat. No. 6,426,274 discloses a method for making a thin film semiconductor. In this method, porous layers having different porosities are formed on a substrate having a surface layer, and an epitaxial semiconductor film formed on a porous structure is mechanically separated from the substrate using the porous structure.
In the meantime, U.S. Pat. Nos. 6,326,280; 6,107,213; 5,811,348; 6,194,245; and 6,194,239 disclose a method for manufacturing a thin film semiconductor and a method of separating a device formation layer from a base body.